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From DuyHai Doan <doanduy...@gmail.com>
Subject Re: query tracing
Date Mon, 10 Nov 2014 15:21:35 GMT
As Jonathan said, it's better to activate query tracing client side. It'll
give you better flexibility of when to turn on & off tracing and on which
table. Server-side tracing is global (all tables) and probabilistic, thus
may not give satisfactory level of debugging.

 Programmatically it's pretty simple to achieve and coupled with a good
logging framework (LogBack for Java), you'll even have dynamic logging on
production without having to redeploy client code. I have implemented it in
Achilles very easily by wrapping over the Regular/Bound/Simple statements
of Java driver and display the bound values at runtime :
https://github.com/doanduyhai/Achilles/wiki/Statements-Logging-and-Tracing#dynamic-statements-logging

On Mon, Nov 10, 2014 at 3:52 PM, Johnny Miller <johnny.p.miller@gmail.com>
wrote:

> Be cautious enabling query tracing. Great tool for dev/testing/diagnosing
> etc.. - but it does persist data to the system_traces keyspace with a TTL
> of 24 hours and will, as a consequence, consume resources.
>
> http://www.datastax.com/dev/blog/advanced-request-tracing-in-cassandra-1-2
>
>
> On 7 Nov 2014, at 20:20, Jonathan Haddad <jon@jonhaddad.com> wrote:
>
> Personally I've found that using query timing + log aggregation on the
> client side is more effective than trying to mess with tracing probability
> in order to find a single query which has recently become a problem.  I
> recommend wrapping your session with something that can automatically log
> the statement on a slow query, then use tracing to identify exactly what
> happened.  This way finding your problem is not a matter of chance.
>
>
>
> On Fri Nov 07 2014 at 9:41:38 AM Chris Lohfink <clohfink85@gmail.com>
> wrote:
>
>> It saves a lot of information for each request thats traced so there is
>> significant overhead.  If you start at a low probability and move it up
>> based on the load impact it will provide a lot of insight and you can
>> control the cost.
>>
>> ---
>> Chris Lohfink
>>
>> On Fri, Nov 7, 2014 at 11:35 AM, Jimmy Lin <y2klyf+work@gmail.com> wrote:
>>
>>> is there any significant  performance penalty if one turn on Cassandra
>>> query tracing, through DataStax java driver (say, per every query request
>>> of some trouble query)?
>>>
>>> More sampling seems better but then doing so may also slow down the
>>> system in some other ways?
>>>
>>> thanks
>>>
>>>
>>>
>>
>

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